The European Union's high representative for foreign affairs Mr Javier Solana told the Macedonian government not to negotiate with "terrorist" ethnic Albanian rebels fighting security forces.
"Let me say clearly it is a mistake to negotiate with terrorists. To negotiate with terrorists in this particular case is a mistake . . . and we will not recommend that," he said after talks with Macedonian President Mr Boris Trajkovski.
Military commanders at NATO are asking the alliance's 19 member countries to be ready with Kosovo troop reinforcements in case the crisis in Macedonia worsens or spreads to southern Serbia, a NATO diplomat said.
The extra troops would be assigned to the NATO-led KFOR peacekeeping force in Kosovo, which has rear bases in Macedonia but no mandate to intervene in the fighting between Macedonian security forces and ethnic Albanian rebels.
KFOR currently has 37,000 troops in Kosovo with another 4,000 in logistics roles in Macedonia, Albania and Greece. Of those 2,800 are in Tetovo, Kumanovo and Skopje, a NATO official said.
NATO has been present in Macedonia since 1998 when diplomatic efforts were under way to end a guerrilla war between Kosovo Albanians and Serbian security forces.
In response to Macedonian pressure, NATO Secretary General Lord Robertson announced yesterday KFOR would beef up its patrols along the mountainous Kosovo-Macedonia border and intercept any rebels trying to cross it.